It is known that the radiator in the cooling circuit of the engine in a truck or the like is larger than the radiator for a passenger car, and consequently proposals have already been made to make up the bundles of tubes in such a radiator from at least two sets of finned tubes which are independent from one another and which are juxtaposed and mounted in parallel between the water boxes of the heat exchanger.
Each of these sets of finned tubes, corresponding to a fraction of the bundle of tubes in the radiator is simpler and easier to manufacture and to manipulate than would be a single bundle corresponding to the juxtaposition of these sets of tubes. In particular, the fins on the tubes in these sets have a surface area which is two (or more) times less than the surface area of the fins which would be fitted to the tubes in a single-assembly bundle. Since these fins are generally made of aluminum and are very thin, e.g. about 0.1 mm, reducing their size greatly facilitates manufacture and assembly of a radiator bundle, and also improves its mechanical behaviour.
However, a heat exchanger whose bundle is built up from two or more independent assemblies of finned tubes which are juxtaposed as close as possible is nevertheless subjected to considerable vibration in use which can cause the fins of said assemblies to strike one another along their facing edges, thereby crushing or otherwise deforming said edges.
Preferred embodiments of the invention avoid these drawbacks in a simple manner which costs little and is particularly effective.